Teach you Vista wallpaper interpolation solution

Although this may not be the point to locate it, it is indeed a flaw and exists in vista RC2. When using images as desktop wallpapers, Windows Vista will be responsible for maintaining the image aspect ratio, but when compared to Windows XP, when the image is stretched to fit the screen resolution, Vista will not interpolate the image. So that there is a sawing phenomenon. In the next two figures, the left image is an example proof of the problem, which clearly lacks interpolation (also known as the jagged edge); it appears smoother.
Vista wallpaper interpolation problem
Sawtooth is caused by the lack of image interpolation. The so-called image interpolation is a process of image data reproduction - it reproduces an image data with high resolution from the original image.
In Vista, JPEG interpolation via the desktop control panel is not performed correctly. One of the most immediate results is that when you stretch a picture with a different screen resolution as a wallpaper, an undesired visual effect will appear. This shortcoming seems to only appear on JPEG images, while BMP images are able to accept correct interpolation from the control panel.
“Set as desktop background” function can solve this problem. The “Set as desktop background" feature takes advantage of the PIX engine used by the Windows Photo Gallery program. PIX supports image interpolation, and when you set a picture as a wallpaper, you can use it well. As for why the Windows Photo Gallery program does not use image interpolation for photos when zooming in on the image, this may be categorized in Microsoft's alternative design.